I catch the RV anti-freeze in the original container. I don't use compressed air, just plain water to de-winterize. I treat the fresh water tank with the proper bleach/water mixture then pump it through the lines. I catch the anti-freeze until it begins to weaken in color, then shut the faucet and go to the next one. RV anti-freeze here is only $2.99/G, but like Ben Franklin said: "watch your pennies and the dollars will watch themselves".
Since it says on the jug it may be diluted from the OEM -50* protection, I use it two years before discarding. Yes, it is environmentally safe to pour down the drain according to the MSDS. I normally use two gallons of RV anti-freeze to winterize, and recover about 1 1/4, the other 3/4 went into "P " traps and holding tanks.
I've never had a frozen water line this way. I did have a frozen line one year when I was persuaded to only use compressed air_lesson learned.
I don't know how winterizing our MH will turn out, this is our first winter for it and us.Might not have to winterize at all if we leave for Naval Air Station Key West after Thanksgiving.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"